import math
x = map(float, (raw_input()).split(" "))

print math.sqrt((x[2]-x[0])*(x[2]-x[0]) + (x[3]-x[1])*(x[3]-x[1])) import math math x = map(float, (raw_input()).split(" ")) x map(float, (raw_input()).split(" ")) map float (raw_input()).split(" ") raw_input()).split raw_input() raw_input split " " print math.sqrt((x[2]-x[0])*(x[2]-x[0]) + (x[3]-x[1])*(x[3]-x[1])) math.sqrt math sqrt (x[2]-x[0])*(x[2]-x[0]) + (x[3]-x[1])*(x[3]-x[1]) (x[2]-x[0])*(x[2]-x[0]) x[2]-x[0] x[2] x 2 x[0] x 0 x[2]-x[0] x[2] x 2 x[0] x 0 (x[3]-x[1])*(x[3]-x[1]) x[3]-x[1] x[3] x 3 x[1] x 1 x[3]-x[1] x[3] x 3 x[1] x 1 x = map(float, (raw_input()).split(" ")) map(float, (raw_input()).split(" ")) x
import math
x = map(float, (raw_input()).split(" "))

print math.sqrt((x[2]-x[0])*(x[2]-x[0]) + (x[3]-x[1])*(x[3]-x[1]))